A concussion indicator that may easily be applied to a helmet is provided. The concussion indicator may visually or audibly provide indicators relating to impacts creating accelerations of the helmet that likely cause a concussion. In some embodiments, three separate indicators may be used within a single base; each indicator is configured to indicate at impacts relating to different concussion grades. A rear of the base is attachable to a surface such as an interior or exterior of a helmet. Upon a concussion triggering acceleration, the concussion indicator will indicate that a concussion is likely. This display may be seen or heard by observers if the indicator is on an exterior of the helmet, and by the user or someone who removes the user's helmet if it is on the inside of the helmet.